Sizing coefficient

C, = Liquid sizing coefficient Q = Flow rate in GPM AP = Body differential pressure, psi G = Specific gravity (water at 60°F = 1.0)... 

The coefficient (p value depends on the source location in the ventilated room (e.g., in the center, close to the wall, etc.) and the source dimensions relative to the room size. Coefficient (p values for small sources (<1/10 of the room size) can be estimated using Tables 7.3. and 7.4. 

Cg - gas sizing coefficient Cs = steam sizing coefficient Cv - liquid sizing coefficient d[ = density of steam or vapor at inlet, lb/ft3 G - gas specific gravity = mol wt/29 P] - valve inlet pressure, psia AP - pressure drop across valve, psi Q - gas flow rate, scfh Qs = steam or vapor flow rate, lb/hr T - absolute temperature of gas at inlet, °R TSh = degrees of superheat, °F... 

For a preliminary design, except for very large or expensive heat exchangers, it is usually adequate to use approximate heat transfer coefficients. These can be found in references 22,23 and 24. When calculating individual heat transfer coefficients, it may simplify calculations to note that for streams that have a viscosity greater than 5 cp the tube-size coefficient is two or three times what the shell-side coefficient would be for the same material.2 This is often the deciding factor in determining which fluid should flow within the tubes. 

C is the valve-sizing coefficient. Density varies with pressure and composition. 

To get convergence with respect to the Bk correction it is sufficient to include the main configurations, their single excitations, and some configurations (normally double excitations with respect to the main configurations) with medium sized coefficients. 

Calculate the required valve sizing coefficient, C , based on process data and manufacturers valve data. 

If, for a given sample, we measured several reflection orders (001), (002), (003) etc., and if we extracted the cos A coefficients, we could plot the evolution of lnA according to P for a set value of n. The y-intercepts give us the size coefficients A T, whereas the coefficients related to the distortions are obtained from the slopes of these lines. 

The control valve is a 2-inch globe valve, with a linear characteristic, a full-travel liquid sizing coefficient Cy = 65.3 US gall/min/psi and a full-travel gas sizing coefficient Cq = 2280 scf/h/psia. The control valve travel is initially 100%, but this is decreased by a 5% per second ramp starting at time = 5 seconds to 5% open at time = 24 seconds. The control valve is then maintained in this position to the end of the transient at time = 30 seconds. 

Equation (A3.15) possesses the limitation that it does not predict the choking effect that will occur when the flow becomes sonic in the valve throat. For such conditions, US manufacturers predict choked flow, Orrir, in terms of the measured gas sizing coefficient . 

C is the gas sizing coefficient (scf/hr/psia) for a given valve opening. 

With the sizing coefficient Cg for a nozzle with a throat area equal to the seat area of the safety valve, the mass flow rate is defined in a dimensionless form ... 

The sizing coefficient for steady-state conditions of an ideal gas through the nozzle without friction and heat exchange with the wall is written as (isentropic flow of an ideal gas)... 

The fluid dynamic critical pressure and the critical pressure ratio r) = Pait/po in a nozzle throat may be calculated by differentiating the sizing coefficient, Eq. (15.21), with respect to the pressure ratio and setting the result equal to zero. Enuther mathematical transformations lead to the critical pressure ratio of a real gas ... 

Figure 15.6 Sizing coefficient versus reduced inlet stagnation pressure calculated according to EN-ISO 4126-7 and a nozzle flow model including real gas effects for ethylene at inlet stagnation temperatures of 300 and 443 K.

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